JP2000283245A - Toothed belt and manufacture thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent fraying of a core wire by embedding a part of outer periphery of the core wire positioned in a groove part into thermoplastic resin in a toothed belt which has a plurality of tooth parts arranged at a fixed interval in the longitudinal direction and a back part in which the core wire is embedded and whose surfaces of the toothed parts are covered with thermoplastic resin having a low melting point and high viscosity. SOLUTION: In a toothed belt 1 which has a plurality of toothed parts 2 arranged at a fixed interval in the longitudinal direction and a back part 4 in which a core wire 3 is embedded and whose surfaces of the tooth parts 2 are covered with thermoplastic resin 5 having a low melting point and high viscosity, 20 to 70% of a diameter of the core wire 3 is embedded in the thermoplastic resin 5, that is, (h/d)×100 is 20 to 70, to bond and fix the core wire 3 firmly by the thermoplastic resin 5. Moreover, a part or all of outer periphery of the core wire 3 is covered with softened thermoplastic resin 5 at the time of rubber vulcanization. Since outer periphery of the core wire 3 is covered with the thermoplastic resin 5, it is possible to obtain high, hardness, cut a belt easily in disconnection of a belt, and prevent the occurrence of fraying.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a toothed belt having a tooth surface coated with a thermoplastic resin having a low melting point and a high viscosity, and more particularly, to a printer carriage belt, and a sheet for conveying bills and cards. The present invention relates to a general industrial toothed belt such as a belt or an automotive toothed belt.

[0002]

2. Description of the Related Art Conventionally used toothed belts such as a printer carriage belt and a paper sheet transport belt for transporting banknotes and cards, etc., are provided between a toothed portion made of rubber and a back portion for reinforcement. The wire is buried, and the tooth surface is covered with a woven fabric made of 6 nylon, 66 nylon, aramid fiber or the like.

However, when the surface of the belt teeth is covered with the woven cloth, appearance defects such as twisting of the belt and warping of the belt occur due to the difference between the contraction rate of the woven cloth and the contraction rate of the rubber. . In addition, the rubber oozes out from the folds of the woven fabric and scatters around the apparatus, which sometimes causes the malfunction of the apparatus and stops the function.

As a countermeasure, a canvas coated only with a resorcinol-formalin-latex solution (hereinafter referred to as an RFL solution) is used as a canvas for covering the tooth surface. There were problems such as the rubber oozing out of the canvas and insufficient formation of teeth due to the variation in the amount. Further, the process up to the immersion treatment in the RFL solution is long, and there is a problem in stability of quality. Furthermore, the cords of the belts whose tooth surfaces are covered with canvas are only buried in the rubber, and the cords are easily frayed, and in particular, the cords are frayed on the side of the belt during running. .

[0005]

Therefore, in order to solve the above-mentioned problems, belts whose teeth are coated with a thermoplastic resin have been developed and used. However, the core wire of the belt whose tooth surface is currently used and coated with a thermoplastic resin is only buried in rubber like the belt whose tooth surface is coated with conventional canvas, Still, the core wire is easily frayed, and particularly, the core wire frays on the side of the belt during running.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and it is intended to prevent the exudation of rubber from a tooth surface and the fraying of a core wire, and to provide a tooth surface excellent in wear resistance and durability. An object of the present invention is to provide a toothed belt coated with a thermoplastic resin and a method for producing the same.

[0007]

According to a first aspect of the present invention, there is provided an electric vehicle comprising a plurality of teeth arranged at regular intervals in a longitudinal direction, and a back having a core wire embedded therein. In a toothed belt in which the surface of a portion is coated with a thermoplastic resin having a low melting point and a high viscosity, a part of an outer periphery of the core wire located in a groove portion is buried in the thermoplastic resin.

[0008] By coating the tooth surface with a thermoplastic resin, it is possible to prevent the rubber from oozing out from the tooth surface. Further, since a part of the core wire is buried in the thermoplastic resin in the groove portion, each core wire is firmly held by the thermoplastic resin, and it becomes possible to prevent the core wire from fraying during running. Here, the low-melting-point, high-viscosity thermoplastic resin refers to a thermoplastic resin that melts or softens depending on the temperature at the time of vulcanization and has a certain degree of viscosity at this time. Specifically, ultrahigh molecular weight polyethylene having a molecular weight of 1750,000 to 2,000,000, polytetrafluoroethylene, ultrahigh viscosity nylon and the like are exemplified. Among them, ultrahigh molecular weight polyethylene is preferable.

Further, in the invention according to claim 2, the core wire located in the groove portion may have a core diameter of 20 to 70 in the thermoplastic resin.
The toothed belt according to claim 1, which is buried in%.

If the percentage of the core wire buried in the thermoplastic resin is less than 20% of the core wire diameter, the adhesive force between the core wire and the thermoplastic resin is reduced, and the core wire on the cut surface such as the side surface of the belt. The problem of fraying is not solved. If the percentage of the core wire buried in the thermoplastic resin exceeds 70% of the core wire diameter, the adhesive strength between the core wire and the rubber decreases. Further, the flexibility of the cord is lost, the rigidity of the entire belt is increased, and the orbit torque of the motor is increased. For this reason, the range of the burial ratio of the core wire in the thermoplastic resin is preferably 20 to 70% of the core wire diameter. More preferably, it is 30 to 60%.

According to a third aspect of the present invention, in the first or second aspect, a part or the entire outer periphery of a portion of the core wire that is not buried in the thermoplastic resin is covered with the thermoplastic resin. It is a toothed belt.

[0012] Since part or all of the outer periphery of the core wire not buried in the thermoplastic resin is covered with the thermoplastic resin, the belt can be easily cut and the core wire is prevented from being frayed. Can be.

Further, according to a fourth aspect of the present invention, a sheet-shaped thermoplastic resin having a low melting point and a high viscosity is wound around a cylindrical or cylindrical mold having a large number of tooth grooves for forming teeth formed on an outer periphery thereof. An unvulcanized rubber sheet forming a core wire and further forming a tooth portion and a back portion thereon is wound thereon, and the pressure is 6.5 to 8.5 kg / cm ^2.
And then vulcanize at 160-175 ° C. to melt and soften the thermoplastic resin at the time of vulcanization, and bury a part of the outer circumference of the core wire located in the groove in the thermoplastic resin This is a method for manufacturing a toothed belt to be made.

According to this method, a part or the whole of the core wire is inserted into the thermoplastic resin in the groove portion at a core wire diameter of 20 to 70%.
% Burial is possible.

[0015]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a perspective view showing the structure of the toothed belt. Here, 1 in the figure is a toothed belt, 2 is a toothed portion, 3 is a core wire, 4 is a back portion, and 5 is a thermoplastic resin.

The rubber used for the tooth portion 2 and the back portion 4 is not particularly limited, but includes chloroprene, natural rubber, millable urethane rubber, hydrogenated nitrile rubber (HN
Rubber having improved heat aging resistance, such as BR), chlorosulfonated polyethylene (CSM), and alkylated chlorosulfonated polyethylene (ACSM) is preferable. The hydrogenated nitrile rubber has a hydrogenation rate of 80% or more, and the hydrogenation rate is preferably 90% or more in order to exhibit heat resistance and ozone resistance. A hydrogenated nitrile rubber having a hydrogenation rate of less than 80% has extremely low heat resistance and ozone resistance. Among the above rubbers, carbon black, zinc white, stearic acid, a plasticizer, an antioxidant, etc. are added as compounding agents, and sulfur and organic peroxides are used as vulcanizing agents. The sulfurizing agent is not particularly limited.

The thermoplastic resin 5 is preferably ultrahigh molecular weight polyethylene, polytetrafluoroethylene, ultrahigh viscosity nylon or the like. Among them, the vulcanization temperature of rubber is 160 to 17
Ultrahigh molecular weight polyethylene having an average molecular weight of 1750,000 to 2,000,000, which is a resin that does not become liquid at 5 ° C., exhibits a softened state, has a low friction coefficient, and is excellent in abrasion resistance, is preferable. Here, the solution viscosity average molecular weight _Mv is used as the average molecular weight. This is obtained by measuring the intrinsic viscosity of the solution and calculating the viscosity according to the following formula (1). _{^{η = 4.60 × 10 -4 M v}} 0.725 (1) where, eta is the intrinsic viscosity.

The core wire 3 may be a commonly used one, but it is preferable to use one having excellent heat resistance, flexibility and excellent bending fatigue. For example,
Twisted filaments of 5 to 9 μm of E glass or high-strength glass are treated with a rubber compound protective agent or RFL liquid, which is an adhesive. Is twisted with 0.5-2.5 denier filament of para-aramid fiber (trade name: Kevlar, Technora) with small tensile strength and adhesive with RFL solution, epoxy solution, isocyanate solution and rubber compound. Treated stranded cords are preferred. Further, it is preferable to use a fiber obtained by liquid crystal-spinning PBO fiber as the core wire 3 because characteristics such as bending fatigue resistance and heat resistance are improved as compared with the E glass and para-aramid fiber. The present invention does not limit the core wire 3 to these.

FIG. 2 is an enlarged view of the vicinity of the core wire 3 of the toothed belt 1 of FIG. In the figure, d indicates the diameter of the core wire 3 and h indicates the burial depth of the core wire 3 in the thermoplastic resin 5. Here, the core wire 3 has a diameter of 20 to 7 in the thermoplastic resin 5.
By burying 0%, that is, when (h / d) × 100 is in the range of 20 to 70, the core wire 3 is firmly adhered and fixed by the thermoplastic resin 5. Further, as shown in the figure, a part or all of the outer periphery of the core wire 3 is covered with the softened thermoplastic resin 5 at the time of rubber vulcanization. Compared with the conventional case where the core wire is simply buried in rubber, the outer periphery of the core wire 3 is covered with the thermoplastic resin 5 so that the hardness is high and the belt is easily cut when cutting the belt. In addition, fraying is less likely to occur. Here, if the percentage of the core 3 buried in the thermoplastic resin 5 is less than 20% of the core diameter, the adhesive force between the core 3 and the thermoplastic resin 5 is reduced, and cutting of the belt side surface or the like is performed. The core wire 3 frays on the surface. If the percentage of the core 3 buried in the thermoplastic resin 5 exceeds 70% of the core diameter, the adhesive strength between the core 3 and the rubbers 2 and 4 decreases.
Further, the flexibility of the core wire 3 is lost, the rigidity of the entire belt 1 is increased, and the starting torque of the motor is increased. For this reason,
The range of the burial ratio of the core wire 3 in the thermoplastic resin 5 is preferably 20 to 70% of the core wire diameter. More preferably, 30
~ 60%.

Next, a method of manufacturing the toothed belt 1 according to the present invention in which the surface of the tooth portion 2 is covered with the thermoplastic resin 5 will be described.

A sheet-shaped thermoplastic resin film is wound around a cylindrical or cylindrical mold having a large number of tooth grooves for teeth formation on the outer periphery, and a core wire is wound thereon. Further, an unvulcanized rubber sheet for forming teeth and a back portion is wound around the core wire. And 6.5-8.5 kg /
After compression at a pressure of cm ² , vulcanization is performed at a temperature of 160 to 175 ° C. for 10 to 30 minutes to form a belt sleeve. When this belt sleeve is cut into a predetermined width, a toothed belt is obtained. At the time of this vulcanization, the thermoplastic resin is melted and softened, and along the tooth gap of the mold, and the core wire is partially buried in the melted and softened thermoplastic resin due to the application of external pressure.

[0022]

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to examples. However, the present invention is not limited to these examples, and can be appropriately changed without departing from the object.

Examples 1 to 3 and Comparative Examples 1 and 2 Three glass fibers of ECG150 were aligned as core wires, and RFL treatment solution [11.0 parts by weight of resorcinol, 8 parts by weight of formalin (37%), 0.1% of caustic soda. 2 parts by weight of a terpolymer of styrene, butadiene and vinylpyridine (40
%) 84.0 parts by weight, chlorosulfonated polyethylene rubber latex (40%) 56.0 parts by weight, water 121.
5 parts by weight], air-dried, and heat-treated at 280 ° C. for 1.5 minutes, and then twisted separately in the S direction and the Z direction at a rate of 12 times / 10 cm to obtain a glass cord. Further, as the material of the back rubber and the tooth rubber, a rubber compound shown in Table 1 was used as a sheet having a thickness of 0.6 mm.

[0024]

[Table 1]

As a thermoplastic resin covering the tooth surface,
Film made of ultra-high molecular weight polyethylene having an average molecular weight of 1750,000 to 2,000,000 (melting point: about 140
° C). By adjusting the thickness of the ultrahigh molecular weight polyethylene film, the ratio of the core wire buried in the ultrahigh molecular weight polyethylene was adjusted.

The ultrahigh molecular weight polyethylene having the adjusted thickness was set in a mold. From above, a pair of S, Z twisted glass core wires are alternately wound spirally at a pitch of 0.5 mm with a winding tension of 3 kg / piece, and a thickness of 0.6 m from above.
m, a pressure of 6 kg / cm ² , a temperature of 160 ° C., and a pressure of 6 kg / cm ² by a conventional press-fitting vulcanization method.
After forming a vulcanized sleeve under the condition of 0 minutes, the vulcanized sleeve was polished to a predetermined thickness and cut into a predetermined width in a ring shape to produce individual belts. The produced belt size is 40S2M
328 (number of teeth: 164, belt width: 4 mm, tooth pitch:
2 mm, belt tooth form: S2M).

The bending stiffness and starting torque of each of the belts manufactured as described above were measured. Further, each belt is hung on a drive pulley having 18 teeth and a driven pulley having 90 teeth, and at a rotation speed of 9000 rpm, 65
A durability test was performed in which the belt was run for 100 hours without a load of W, and the appearance of the belt after the test was observed.

(Method of Measuring Bending Stiffness) FIG. 3 shows an apparatus for measuring the bending stiffness of a belt. The bending stiffness of the belt is set such that the cut belt 1 is set on the sample setting table 17 shown in the figure and is protruded from the end of the table 17 by 10 teeth in a room adjusted to a predetermined temperature, and the protruding belt end The load is applied by vertically moving the torsion-type tension gauge 16 downward using a motor 19 and a ball screw 20. Then, the value of the hook-type tension gauge 16 when the protruding belt 1 was bent 21 and the belt 1 came into contact with one surface 18 of the sample setting table was defined as the bending rigidity of the belt 1.

(Starting Torque Measuring Method) FIG. 4 shows a starting torque measuring device. In a room adjusted to a predetermined temperature, FIG.
In order to hang the belt 1 on the fixed driving pulley 24 (number of teeth 20) and the movable driven pulley 25 on the starting torque measuring device 23 shown in FIG.
The driven pulley 25 is moved to apply an axial load of 600 gf to the belt. Then, the weight 26 is suspended from the driven pulley 25, the weight 26 is gradually increased, the pulley rotates, and the minimum load W when the weight 26 descends by 5 cm is measured and calculated by the following equation. Starting torque = (W−W ₀ ) × 0.65 Here, W ₀ is a load by which the weight 26 descends by 5 cm or more when the belt is not worn.

Table 2 and FIG. 5 summarize the above results.

[0031]

[Table 2]

As can be seen from Table 2 and FIG. 5, the belts of Examples 1 to 3 in which the core wire is buried 20 to 70% of the core wire diameter in the ultra high molecular weight polyethylene covering the tooth surface, After the endurance test, there was no fraying of the core wire and no fuzz on the side of the belt. On the other hand, it can be seen that the bending stiffness and the starting torque of the belt of Comparative Example 1 buried by 84% of the core wire diameter sharply increased. In the belt of Comparative Example 2, fraying and fluffing of the core wire on the side surface of the belt were observed after the durability test.

[0033]

According to the present invention, the tooth surface is covered with a thermoplastic resin, so that the tooth shape is clearly formed without the rubber oozing out on the tooth surface, so that the rubber powder is not scattered during running of the belt.

Further, at least a part of the core is buried in the thermoplastic resin covering the tooth surface in the groove, and a part or all of the outer periphery of the core is covered with the thermoplastic resin. The wire is held firmly by the thermoplastic resin,
Fraying and fluffing of the core wire during and after running are less likely to occur. Further, by controlling the amount of the core wire buried in the thermoplastic resin, it is possible to prevent the core wire from fraying and fuzzing without inhibiting the function of the belt.

[Brief description of the drawings]

FIG. 1 is a schematic perspective view of a toothed belt according to the present invention.

FIG. 2 is a diagram for explaining the amount of core wire buried in a thermoplastic resin.

FIG. 3 is a schematic view of an apparatus for measuring the bending stiffness of a toothed belt according to the present invention.

FIG. 4 is a schematic view of a starting torque measuring device for a toothed belt according to the present invention.

FIG. 5 is a diagram showing a relationship between a starting torque, a bending rigidity of a belt, and a burial amount of a core wire.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Toothed belt 2 Tooth part 3 Core wire 4 Back part 5 Thermoplastic resin 15 Flexural rigidity measuring device 16 Ounce type tension gauge 17 Sample setting table 18 Sample setting table 19 Motor 20 Ball screw 21 Belt bending angle 23 Starting torque measuring device 24 Drive Side pulley 25 Follower side pulley 26 Weight

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Shunichi Takada 4-1-1-21 Hamazoedori, Nagata-ku, Kobe-shi, Hyogo Prefecture Inside Mitsuboshi Belting Co., Ltd. (72) Namiko Seki 4-1-1, Hamazodori, Nagata-ku, Kobe-shi, Hyogo No. 21 Mitsuboshi Belting Co., Ltd. (72) Inventor Masahisa Fujita 4-1-1 Hamazoedori, Nagata-ku, Kobe City, Hyogo Prefecture F-term inside Mitsuboshi Belting Co., Ltd. 3F024 AA03 AA11 CA08 CB03 CB09 CB13 DA03 DA13 4F213 AA45 AD15 AD18 AG17 AH12 WA31 WA53 WA87 WB01

Claims (4)

[Claims] 1. A toothed body having a plurality of teeth arranged at regular intervals in a longitudinal direction and a back part having a core wire embedded therein, wherein the surface of the teeth is coated with a thermoplastic resin having a low melting point and a high viscosity. A toothed belt in which a part of an outer periphery of the core wire located in a groove is buried in the thermoplastic resin. 2. A core wire located in the groove portion is buried in the thermoplastic resin by 20 to 70% of a core wire diameter.
The toothed belt as described. 3. The toothed belt according to claim 1, wherein a part or the entire outer periphery of a portion of the core wire that is not buried in the thermoplastic resin is covered with the thermoplastic resin. 4. A sheet-shaped thermoplastic resin having a low melting point and a high viscosity is wound around a cylindrical or cylindrical mold having a large number of tooth grooves for forming a tooth portion formed on an outer periphery thereof, and a core wire is further formed thereon. An unvulcanized rubber sheet forming teeth and a back portion is wrapped thereon and compressed from the outside at a pressure of 6.5 to 8.5 kg / cm ² ,
A method of manufacturing a toothed belt in which the thermoplastic resin is vulcanized at 0 to 175 ° C., and the thermoplastic resin is melted and softened during the vulcanization, and a part of the outer periphery of a core wire located in a groove is buried in the thermoplastic resin. .